(1) Field of the Invention
The present invention relates to a method for developing a uniform red color in cured meat, particularly fermented meats containing nitrate and/or nitrite. In particular, the present invention uses (a) a nitrate reducing bacteria, particularly Micrococcus, and (b) a Streptococcus lactis subspecies diacetylactis which acts in the presence of nitrite produced by a reduction of food grade nitrate to develop a cured red color. The Streptococcus lactis subspecies diacetylactis produces a red color in the meat at an early stage of the cure in the presence of nitrite without significant drop in pH (development of acid). The nitrite can be supplied by the nitrate reducing bacteria. Further development of the cured red color at a late stage of the cure is intensified by a reduction in pH by a lactic acid producing culture.
(2) Prior Art
The use of lactic acid producing Streptococcus lactis cultures to inhibit spoilage bacteria in ground meat is described by Reddy, S. G. et al in Journal of Food Science 35, 787-791 (1970). Streptococcus lactis subspecies diacetylactis strain is disclosed along with the suggestion that this subspecies generates an inhibitory substance which inhibits spoilage microorganisms. Ascorbic acid was added with the cultures of Streptococcus lactis to maintain the appearance of the ground meat which tended to oxidize to a brown color. The brown color is regarded by the consumer as an indication of a lack of freshness. When lactose was added to the cultures the inhibitory affect was increased, most likely because of the generation of lactic acid by the Streptococcus lactis from the lactose. Thus to a significant extent the inhibition achieved by Reddy et al are attributed to the lactic acid producing capabilities of the strains of Streptococcus lactis used. No edible nitrite was added to the meat and thus no cured red color was developed.
U.S. Pat. No. 3,814,817 to Everson et al describes the use of mixtures of lactic acid producing bacteria and Streptococcus diacetilactis in fermenting meat in the presence of food grade nitrite or nitrate. This patent suggests that it is desirable to maintain the natural cure color of the meat without any further discussion. U.S. Pat. No. 3,561,977 to Rothchild et al generally describes meat fermenting processes using lactic acid producing bacteria.
U.S. Pat. No. 4,477,471 to Gonzalez describes strains of Streptococcus lactis subspecies diacetylactis which lack the ability to produce lactic acid from lactose but which continue to generate an inhibitory substance effective against food spoilage microorganisms. The strains have been "cured" to rmove a 41 Mdal plasmid which encodes for lactic acid production from lactose while retaining the ability to produce the inhibitory substance. These strains are described as being useful in milk fermentations; however, there is no suggestion that they would be useful in curing meat.
The development of a cured red color in meat is very desirable. This prevents the dark brown color which the consumer regards as spoilage. U.S. Pat. No. 4,304,868 to Gryczka and Shah describe the use of Micrococcus varians, particularly NRRL-B-15,306, with lactic acid producing bacteria to develop a cured red color from nitrite and/or nitrate. Bacteria such as Micrococcus sp. NRRL-B-8048, as described in U.S. Pat. No. 4,013,797 to Gryczka are known to reduce nitrate or nitrite to develop the cured red color in meat. As far as is known, the use of Streptococcus lactis subspecies diacetilactis with a nitrate reducing bacteria to develop a cured red color in meat is unknown. The reason is that Streptococcus lactis subspecies diacetylactis is not used commercially in meat fermentations and it is believed that the use of this species to develop an early red color in meat in the presence of a food grade nitrite is unknown.